Well you're in luck, because I'm a bit of a history buff and absolutely have you covered here: 'Grant' by Ron Chernow (wrote fantastic books about Washington and Hamilton as well), is pretty much the definitive history of the man and entirely debunks all the lies and ill-repute his reputation has received over the years.
It's a long read, 800 pages if I remember correctly, but incredibly fascinating and my favorite book on any American history subject other than WWII. There's an audiobook version if that's easier for you, but I myself prefer paper (personal preference). Either is solid and I cannot recommend it enough. It should be mandatory reading in schools.
